[Amps] LK500 Question from New Subscriber

[Bob Maser]

Each tube needs ±13CFM @ .082" water pressure so 2 tubes need 26CFM at the 
same pressure.  Try looking for an EBM Pabst centrifugal blower.  They are 
very quiet and small.  I have a EBM G2E085-AA05 blower that would do the 
job.  Make me an offer after you have done your search.

Bob  W6TR
----- Original Message ----- 
From: "Charlie Young" <weeksmgr at hotmail.com>
To: <amps at contesting.com>
Sent: Monday, April 27, 2009 2:10 PM
Subject: [Amps] LK500 Question from New Subscriber



Hi Folks:  I am a long time reader of the Amps archives, and finally decided 
to subscribe.  The amount of expertise available on this list is phenomenal, 
and several of you have helped me over the years, either with your postings 
here or by answering questions sent directly by me. All of the help is 
appreciated. With retirement last year, there is now time to pursue my 
interest in amplifiers.



Recently, I acquired a LK500ZB in an estate sale, and it exhibited the tube 
socket heating/filament pin solder melting issue that has been described on 
here. This one has a high/low speed switch factory installed for the blower, 
and the problem was a cold solder joint on one of the series dropping 
resistors, causing the cooling fan to run at a very low speed all the time. 
I replaced the tube sockets, resoldered the tube filament pins, and replaced 
the plate choke; the amp now runs fine, and puts out ~1500 W when pushed 
(which I don't do when operating).  However, the fan in this amp is 
extremely noisy, to the point where it is annoying to use.



Does anyone know what the CFM rating on this fan is supposed to be? It is a 
NIDEC TORIN TA450 115V Model A30045-10.  The fan is obsolete, and I can find 
no data from the manufacturer online.  I likely would replace this fan if I 
could find another with adequate CFM and a lower noise level.



Likewise, I have searched and can find no recommendation for how much air 
should be directed across a 3-500 when using a transverse airflow like the 
LK500 and SB220.  I might have missed it, but did look for it.  Does anyone 
know wht this airflow requirement is in the application?



Currently, I am running the fan with a standard value dropping resistor used 
by Amp Supply on their high speed position, and there is no way that I am 
going to slow this fan down and reduce CFM to drop the noise level.



Any suggestions or answers to my questions would be appreciated.



73, Chas N8RR



Likewise, I have not been able to find

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